how much weight would a perfect vacumm lift?

Question

suppose I have a perfect vacumm and the container that holds it is weightless. (I know this can't be done but just assume)

how much weight would a 1 cubic meter vacumm (with no weight) lift in normal air. (laws of buoyancy).

I would want to see some math.

Answer 1

Using Archimedes' principle, it would lift a weight equal to the weight of 1 m^3 of air at whatever temperature and pressure air existed around the container.

Standards texts give this, for sea level std conditions as

1.29274 kg

Since this is a mass unit, one must multiply by g (9.8 m/s^2) to get the true answer in force units of

12.67 newtons or 2.85 lb

Answer 2

As was already said, a vacuum doesn't lift anything.

I'll make that container cover 1000 square inches. At atmospheric pressure of around 15 pounds per square inch, I could make it lift 15,000 pounds (but for an exceedingly short distance).

I'd rather remove your 'in normal air' restriction and take that same container to the bottom of the Marianas Trench, where the pressure is about 100 atmospheres (see reference). There, it would lift 1,500,000 pounds.

This container would be a cylinder with fixed top and perimeter anchored to the earth, and a movable bottom attached to the weight to be lifted. This isn't buoyancy. It's the pressure exerted by a fluid (air or water) against a surface with zero pressure exerted on the other side of the surface.

Answer 3

Perfect vacuum is just that. It is vacuum, therefore what makes you think that it will lift something ? Perfect Vacuum is not a force of any kind. In space where there is vacuum the forces of gravitational pull of planets can be experienced. Even with this force the Astronauts have to be tethered to the space ship or else they will float away. So I do not think that perfect vacumm would lift anything. The moment you mention buoyancy, you have to know that we are talking about Fluid and not Perfect vacuum.

Answer 4

There are five laws that are true for all observed phenomena in science. The one that dominates here is balance of momentum.

The material derivative for is F = d(m*v)/dt
in the case of constant mass with respect to time, or in this case, constant local air density, this becomes the familiar F = m*a

First draw two body diagrams.
In your first one you have your body, with a downward force arrow for the restraining force, and an upward force arrow for the lifting force. Upon it you impose equilibrium.
In the second one you have a dotted line the exact shape of your body, but air inside and outside of it. It is a parcel of ambient air. It is in equilibrium, not moving up nor down.

The external forces, except gravity, on the parcel of air, and on your parcel of vacuum are identical. The parcel is made of your container, its just filled with air at equilibrium to the environment.

The parcel of air has no lift.
The downward load on the parcel of air is the gravitational force between the air and the earth, or density*volume*gravitational acceleration. This exactly balances the external forces that would otherwise cause buoyancy.

The equation representing the lifting for is
L = rho*V*g
L is lifting force
rho is density of air
V is volume
g is gravitational acceleration.

lets say its air at stp, sea level. Its about 1/1000 the density of liquid water, or about 1 micgrogram per cubic centimeter. That works out to about 1 kilogram per cubic meter.
gravitational acceleration at sea level is 9.81 m/s^2.

Multiplying it out, the lifting force is 9.81 Newtons, and it would be able to lift any weight under 1 kilogram.

Answer 5

No. you do not construct muscle contained in the health club, lifting heavy weights tears the muscle fibres. that's by relax and food that you fix the muscle and it grows higher than before. in case you probably did weights all nighttime and were given no relax and devour few energy you ought to extremely get smaller.

Answer 6

A vacuum doesn't lift anything. Outside pressure pushes things into a vacuum.

BTW you misspelled vacuum.

Answer 7

76 cm of mercury due to earth atmosphere at sea level.

Answer 8

I don't know why you would even care about this, but I do know that it would really suck.